Influence of dietary roughage level and Megasphaera elsdenii on feedlot performance and carcass composition of thin cull beef cows fed for a lean market

Abstract

One hundred forty-four cull cows (body condition score = 2.10 ± 0.61; BW = 456 ± 47 kg) were organized into a 2 × 2 factorial design (48 pens, 12 pens/treatment, and 3 cows/pen) to evaluate the effect of dietary roughage level and oral drenching of Megasphaera elsdenii NCIMB 41125 (M. elsdenii culture; Lactipro Advance; MS Biotec Inc., Wamego, KS) on performance and carcass characteristics. Cattle were finished over a 42-day realimentation period, and aggressively stepped up over a 10-day period to either a high roughage finisher (HRF; 25% roughage) or a low roughage finisher (LRF; 10% roughage). Within diet, cattle were administered no probiotic or 100 mL of M. elsdenii culture (M. elsdenii NCIMB 41125, 2 108 cfu/mL) on day 0. No diet × probiotic interactions were detected (P ≥ 0.15), suggesting that the magnitude of the response was not influenced by the concentrate level of the diet. The main effect of diet triggered several significant responses. Decreasing roughage level tended to improve average daily gain (ADG) by 9.7% (0.26 kg, P = 0.08), while decreasing dry matter intake (DMI) by 0.9 kg (P = 0.09), provoking a 19.7% enhancement of feed efficiency (0.036 units, P < 0.01). However, interim data revealed declines of performance parameters among both diets with a significant difference between treatments only documented during the final phase of the realimentation period. During the final 14 days, LRF posted a 0.68 kg increase in ADG (P = 0.05) and a 2.0 kg decrease in DMI (P = 0.01), translating to improved feed efficiency (0.054 units, P = 0.03). This suggests that increasing the caloric density of finishing diets may help offset the regression of performance typically observed following a compensatory gain. No carcass traits were impacted by either diet or M. elsdenii culture (P ≥ 0.08). Overall, oral drenching of M. elsdenii culture tended to augment ADG (0.26 kg, P = 0.08) and carcass ADG (0.20 kg, P = 0.10). Implying that M. elsdenii culture was effective at alleviating the acidosis risk prompted by the rapid step-up period employed in the trial and may help capitalize on the narrow timeline of compensatory gain in cull cow realimentation.

The influence of Megasphaera elsdenii on rumen morphometrics of cull cows immediately stepped up to a high-energy finishing diet

“…Live animal gain was not the primary focus of this study, as cattle were comingled in group housing, precluding the ability to analyze DMI and G:F. Oral drenching of M. elsdenii culture elicited a 15% numerical improvement in ADG (2.41 vs. 2.09 kg, P = 0.32) over the 35-d trial. Although the value was not significant, it echoes the 9.7% improvement (2.9 vs. 2.7 kg, P = 0.08) in ADG documented over a 42-d finishing period observed by DeClerck et al (2019) . The cattle in both these trials were managed in an analogous fashion with a few caveats.…”

“…The current findings concur with those of Bannink et al (2008) , who noted that maximum papillae area could be obtained in 3 to 4 wk with high-intensity feeding regiments, compared to 7 to 8 wk with conservative diets in transitioning dairy cows. Given the documented improvement in VFA absorption resulting from increased papillae area ( Dirksen et al, 1985 ), the rapid dietary adoption of caloric-rich grain diets utilized in this protocol may help explain the uncharacteristically high ADG and G:F ratios observed in Table 2 as well as by DeClerck et al (2019) .…”

“…The cattle in the referenced trial were housed three per pen, with a 10-d step-up period and 42-d finishing phase. The diet employed in the current study was the same as the low roughage finisher (LRF treatment) from DeClerck et al (2019) . With performance not the primary focus of this study, failing to achieve significant power was not surprising.…”

Effects of Megasphaera elsdenii administration on performance and carcass traits of finishing Bos indicus feedlot cattle

“…Megasphaera elsdenii is a gram-negative bacterium that consumes a major fraction of lactic acid produced in the rumen ( Counotte et al, 1981 ) and, therefore, reduces the occurrence of rumen acidosis ( Kung and Hession, 1995 ). The utilization of a commercial patented strain (Lactipro NXT; M. elsdenii NCIMB 41125) has demonstrated positive results in controlling acidosis under in vitro ( Horn et al, 2009 ; McDaniel et al, 2009 ) and in vivo ( Drouillard et al, 2012 ; DeClerck et al, 2020a ; DeClerck et al, 2020b ; DeClerk et al, 2020c ) experimental settings.…”

“…Megasphaera elsdenii ( MEG ), a gram-negative, lactate-utilizing bacteria seems to be a feasible alternative for maintaining rumen health ( Counotte et al, 1981 ), since under in vitro and in vivo settings, its inoculation alleviated the decrease in pH when increasing amounts of concentrates were inoculated in the medium or fed to the animals ( Kung and Hession, 1995 ; McDaniel et al, 2009 ). Nonetheless, most of the published studies in the literature have evaluated MEG inoculation in different step-up diets management ( Drouillard et al, 2012 ; DeClerck et al, 2020a ; DeClerck et al, 2020b ), whereas no other study evaluated its efficacy on performance of Bos taurus indicus animals receiving a high-energy diet throughout the feedlot period, without offering an adaptation diet. Based on this rationale, we hypothesized that MEG inoculation at the beginning of the feedlot period would increase performance and carcass traits of feedlot animals, even without the offer of an adaptation diet.…”